In a conventional image pickup apparatus such as a digital camera or video camera, all or some of the image pickup lenses are driven by a motor, whereby an auto-focusing function is performed. However, such a method has failed to provide desired focusing performance due to the backlash of the gear system for transmitting motor power. In particular, in the video camera, the motor noises as well as the sound have been recorded.
Thus, a technique has been proposed to minimize the chance of the motor noise being recorded and to improve focusing performance. According to this proposal, a focusing motor is used for rough focusing and a polymer actuator is employed for accurate focusing. An image pickup lens is wobbled by the polymer actuator to detect the focused state and lens traveling direction (Patent Japanese Unexamined Patent Application Publication No. 2007-94237)
In the method disclosed in Japanese Unexamined Patent Application Publication No. 2007-94237, however, the drive shaft of the focusing motor and guide shaft are mounted outside the lens holding frame. This structure increases the outside dimension of the lens drive apparatus and cannot be applied to a microminiaturized image pickup apparatus such as a mobile phone with a built-in camera having appeared in recent years. Although the probability of using the focusing motor is small, the motor noise can be recorded when the focusing motor is used. This does not solve the problem.
An object of the present invention is to solve the aforementioned problem and to provide an optical unit and image pickup apparatus which are characterized by compact configuration, high performance, and minimized noise and which are preferably used in a mobile phone with a built-in camera.